Theorem simp221

Simplification of conjunction. (Contributed by NM, 9-Mar-2012.)

Conclusion
\( \vdash \eta \wedge (\theta \wedge (\varphi \wedge \psi \wedge \chi) \wedge \tau) \wedge \zeta \rightarrow \varphi \)
Proof
simp21
3ad2ant2 _